Merge tag 'drm-fixes-2021-10-08' of git://anongit.freedesktop.org/drm/drm
[linux-2.6-microblaze.git] / fs / 9p / cache.c
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * V9FS cache definitions.
4  *
5  *  Copyright (C) 2009 by Abhishek Kulkarni <adkulkar@umail.iu.edu>
6  */
7
8 #include <linux/jiffies.h>
9 #include <linux/file.h>
10 #include <linux/slab.h>
11 #include <linux/stat.h>
12 #include <linux/sched.h>
13 #include <linux/fs.h>
14 #include <net/9p/9p.h>
15
16 #include "v9fs.h"
17 #include "cache.h"
18
19 #define CACHETAG_LEN  11
20
21 struct fscache_netfs v9fs_cache_netfs = {
22         .name           = "9p",
23         .version        = 0,
24 };
25
26 /*
27  * v9fs_random_cachetag - Generate a random tag to be associated
28  *                        with a new cache session.
29  *
30  * The value of jiffies is used for a fairly randomly cache tag.
31  */
32
33 static
34 int v9fs_random_cachetag(struct v9fs_session_info *v9ses)
35 {
36         v9ses->cachetag = kmalloc(CACHETAG_LEN, GFP_KERNEL);
37         if (!v9ses->cachetag)
38                 return -ENOMEM;
39
40         return scnprintf(v9ses->cachetag, CACHETAG_LEN, "%lu", jiffies);
41 }
42
43 const struct fscache_cookie_def v9fs_cache_session_index_def = {
44         .name           = "9P.session",
45         .type           = FSCACHE_COOKIE_TYPE_INDEX,
46 };
47
48 void v9fs_cache_session_get_cookie(struct v9fs_session_info *v9ses)
49 {
50         /* If no cache session tag was specified, we generate a random one. */
51         if (!v9ses->cachetag) {
52                 if (v9fs_random_cachetag(v9ses) < 0) {
53                         v9ses->fscache = NULL;
54                         kfree(v9ses->cachetag);
55                         v9ses->cachetag = NULL;
56                         return;
57                 }
58         }
59
60         v9ses->fscache = fscache_acquire_cookie(v9fs_cache_netfs.primary_index,
61                                                 &v9fs_cache_session_index_def,
62                                                 v9ses->cachetag,
63                                                 strlen(v9ses->cachetag),
64                                                 NULL, 0,
65                                                 v9ses, 0, true);
66         p9_debug(P9_DEBUG_FSC, "session %p get cookie %p\n",
67                  v9ses, v9ses->fscache);
68 }
69
70 void v9fs_cache_session_put_cookie(struct v9fs_session_info *v9ses)
71 {
72         p9_debug(P9_DEBUG_FSC, "session %p put cookie %p\n",
73                  v9ses, v9ses->fscache);
74         fscache_relinquish_cookie(v9ses->fscache, NULL, false);
75         v9ses->fscache = NULL;
76 }
77
78 static enum
79 fscache_checkaux v9fs_cache_inode_check_aux(void *cookie_netfs_data,
80                                             const void *buffer,
81                                             uint16_t buflen,
82                                             loff_t object_size)
83 {
84         const struct v9fs_inode *v9inode = cookie_netfs_data;
85
86         if (buflen != sizeof(v9inode->qid.version))
87                 return FSCACHE_CHECKAUX_OBSOLETE;
88
89         if (memcmp(buffer, &v9inode->qid.version,
90                    sizeof(v9inode->qid.version)))
91                 return FSCACHE_CHECKAUX_OBSOLETE;
92
93         return FSCACHE_CHECKAUX_OKAY;
94 }
95
96 const struct fscache_cookie_def v9fs_cache_inode_index_def = {
97         .name           = "9p.inode",
98         .type           = FSCACHE_COOKIE_TYPE_DATAFILE,
99         .check_aux      = v9fs_cache_inode_check_aux,
100 };
101
102 void v9fs_cache_inode_get_cookie(struct inode *inode)
103 {
104         struct v9fs_inode *v9inode;
105         struct v9fs_session_info *v9ses;
106
107         if (!S_ISREG(inode->i_mode))
108                 return;
109
110         v9inode = V9FS_I(inode);
111         if (v9inode->fscache)
112                 return;
113
114         v9ses = v9fs_inode2v9ses(inode);
115         v9inode->fscache = fscache_acquire_cookie(v9ses->fscache,
116                                                   &v9fs_cache_inode_index_def,
117                                                   &v9inode->qid.path,
118                                                   sizeof(v9inode->qid.path),
119                                                   &v9inode->qid.version,
120                                                   sizeof(v9inode->qid.version),
121                                                   v9inode,
122                                                   i_size_read(&v9inode->vfs_inode),
123                                                   true);
124
125         p9_debug(P9_DEBUG_FSC, "inode %p get cookie %p\n",
126                  inode, v9inode->fscache);
127 }
128
129 void v9fs_cache_inode_put_cookie(struct inode *inode)
130 {
131         struct v9fs_inode *v9inode = V9FS_I(inode);
132
133         if (!v9inode->fscache)
134                 return;
135         p9_debug(P9_DEBUG_FSC, "inode %p put cookie %p\n",
136                  inode, v9inode->fscache);
137
138         fscache_relinquish_cookie(v9inode->fscache, &v9inode->qid.version,
139                                   false);
140         v9inode->fscache = NULL;
141 }
142
143 void v9fs_cache_inode_flush_cookie(struct inode *inode)
144 {
145         struct v9fs_inode *v9inode = V9FS_I(inode);
146
147         if (!v9inode->fscache)
148                 return;
149         p9_debug(P9_DEBUG_FSC, "inode %p flush cookie %p\n",
150                  inode, v9inode->fscache);
151
152         fscache_relinquish_cookie(v9inode->fscache, NULL, true);
153         v9inode->fscache = NULL;
154 }
155
156 void v9fs_cache_inode_set_cookie(struct inode *inode, struct file *filp)
157 {
158         struct v9fs_inode *v9inode = V9FS_I(inode);
159
160         if (!v9inode->fscache)
161                 return;
162
163         mutex_lock(&v9inode->fscache_lock);
164
165         if ((filp->f_flags & O_ACCMODE) != O_RDONLY)
166                 v9fs_cache_inode_flush_cookie(inode);
167         else
168                 v9fs_cache_inode_get_cookie(inode);
169
170         mutex_unlock(&v9inode->fscache_lock);
171 }
172
173 void v9fs_cache_inode_reset_cookie(struct inode *inode)
174 {
175         struct v9fs_inode *v9inode = V9FS_I(inode);
176         struct v9fs_session_info *v9ses;
177         struct fscache_cookie *old;
178
179         if (!v9inode->fscache)
180                 return;
181
182         old = v9inode->fscache;
183
184         mutex_lock(&v9inode->fscache_lock);
185         fscache_relinquish_cookie(v9inode->fscache, NULL, true);
186
187         v9ses = v9fs_inode2v9ses(inode);
188         v9inode->fscache = fscache_acquire_cookie(v9ses->fscache,
189                                                   &v9fs_cache_inode_index_def,
190                                                   &v9inode->qid.path,
191                                                   sizeof(v9inode->qid.path),
192                                                   &v9inode->qid.version,
193                                                   sizeof(v9inode->qid.version),
194                                                   v9inode,
195                                                   i_size_read(&v9inode->vfs_inode),
196                                                   true);
197         p9_debug(P9_DEBUG_FSC, "inode %p revalidating cookie old %p new %p\n",
198                  inode, old, v9inode->fscache);
199
200         mutex_unlock(&v9inode->fscache_lock);
201 }
202
203 int __v9fs_fscache_release_page(struct page *page, gfp_t gfp)
204 {
205         struct inode *inode = page->mapping->host;
206         struct v9fs_inode *v9inode = V9FS_I(inode);
207
208         BUG_ON(!v9inode->fscache);
209
210         return fscache_maybe_release_page(v9inode->fscache, page, gfp);
211 }
212
213 void __v9fs_fscache_invalidate_page(struct page *page)
214 {
215         struct inode *inode = page->mapping->host;
216         struct v9fs_inode *v9inode = V9FS_I(inode);
217
218         BUG_ON(!v9inode->fscache);
219
220         if (PageFsCache(page)) {
221                 fscache_wait_on_page_write(v9inode->fscache, page);
222                 BUG_ON(!PageLocked(page));
223                 fscache_uncache_page(v9inode->fscache, page);
224         }
225 }
226
227 static void v9fs_vfs_readpage_complete(struct page *page, void *data,
228                                        int error)
229 {
230         if (!error)
231                 SetPageUptodate(page);
232
233         unlock_page(page);
234 }
235
236 /*
237  * __v9fs_readpage_from_fscache - read a page from cache
238  *
239  * Returns 0 if the pages are in cache and a BIO is submitted,
240  * 1 if the pages are not in cache and -error otherwise.
241  */
242
243 int __v9fs_readpage_from_fscache(struct inode *inode, struct page *page)
244 {
245         int ret;
246         const struct v9fs_inode *v9inode = V9FS_I(inode);
247
248         p9_debug(P9_DEBUG_FSC, "inode %p page %p\n", inode, page);
249         if (!v9inode->fscache)
250                 return -ENOBUFS;
251
252         ret = fscache_read_or_alloc_page(v9inode->fscache,
253                                          page,
254                                          v9fs_vfs_readpage_complete,
255                                          NULL,
256                                          GFP_KERNEL);
257         switch (ret) {
258         case -ENOBUFS:
259         case -ENODATA:
260                 p9_debug(P9_DEBUG_FSC, "page/inode not in cache %d\n", ret);
261                 return 1;
262         case 0:
263                 p9_debug(P9_DEBUG_FSC, "BIO submitted\n");
264                 return ret;
265         default:
266                 p9_debug(P9_DEBUG_FSC, "ret %d\n", ret);
267                 return ret;
268         }
269 }
270
271 /*
272  * __v9fs_readpages_from_fscache - read multiple pages from cache
273  *
274  * Returns 0 if the pages are in cache and a BIO is submitted,
275  * 1 if the pages are not in cache and -error otherwise.
276  */
277
278 int __v9fs_readpages_from_fscache(struct inode *inode,
279                                   struct address_space *mapping,
280                                   struct list_head *pages,
281                                   unsigned *nr_pages)
282 {
283         int ret;
284         const struct v9fs_inode *v9inode = V9FS_I(inode);
285
286         p9_debug(P9_DEBUG_FSC, "inode %p pages %u\n", inode, *nr_pages);
287         if (!v9inode->fscache)
288                 return -ENOBUFS;
289
290         ret = fscache_read_or_alloc_pages(v9inode->fscache,
291                                           mapping, pages, nr_pages,
292                                           v9fs_vfs_readpage_complete,
293                                           NULL,
294                                           mapping_gfp_mask(mapping));
295         switch (ret) {
296         case -ENOBUFS:
297         case -ENODATA:
298                 p9_debug(P9_DEBUG_FSC, "pages/inodes not in cache %d\n", ret);
299                 return 1;
300         case 0:
301                 BUG_ON(!list_empty(pages));
302                 BUG_ON(*nr_pages != 0);
303                 p9_debug(P9_DEBUG_FSC, "BIO submitted\n");
304                 return ret;
305         default:
306                 p9_debug(P9_DEBUG_FSC, "ret %d\n", ret);
307                 return ret;
308         }
309 }
310
311 /*
312  * __v9fs_readpage_to_fscache - write a page to the cache
313  *
314  */
315
316 void __v9fs_readpage_to_fscache(struct inode *inode, struct page *page)
317 {
318         int ret;
319         const struct v9fs_inode *v9inode = V9FS_I(inode);
320
321         p9_debug(P9_DEBUG_FSC, "inode %p page %p\n", inode, page);
322         ret = fscache_write_page(v9inode->fscache, page,
323                                  i_size_read(&v9inode->vfs_inode), GFP_KERNEL);
324         p9_debug(P9_DEBUG_FSC, "ret =  %d\n", ret);
325         if (ret != 0)
326                 v9fs_uncache_page(inode, page);
327 }
328
329 /*
330  * wait for a page to complete writing to the cache
331  */
332 void __v9fs_fscache_wait_on_page_write(struct inode *inode, struct page *page)
333 {
334         const struct v9fs_inode *v9inode = V9FS_I(inode);
335         p9_debug(P9_DEBUG_FSC, "inode %p page %p\n", inode, page);
336         if (PageFsCache(page))
337                 fscache_wait_on_page_write(v9inode->fscache, page);
338 }